1. Field of the Invention
This invention relates to a mechanism for controlling the dispersion of flexible, high rate of fire, gun systems.
A flexible gun system, as distinguished from a fixed, forward firing gun system, is one which is continuously directed during target engagement for movement in both the vertical and horizontal planes. Dispersion control is the continuous adjustment of the size, density, shape and orientation relative to the target of the ballistic pattern during the tracking and/or firing interval. Conventional flexible gun system performance is largely influenced by the nature of the tracking and gun-order errors which are stochastically (statistically) non-stationary because of glint, projectile time of flight, etc., and by inherent range-dependent biases such as dynamic servo lag due to target angular acceleration. Dispersion control enhances this performance by essentially "matching" these systematic errors and inherent system biases with appropriate values of random or ballistic dispersion. This process thereby ensures that when a large number of projectiles is placed rapidly in the vicinity of the target, hits will result in the small target subarea which is vulnerable to the striking projectiles.
For high firing-rate single- or multi-barrel flexible gun systems firing a plurality of projectiles sequentially in a uniform series, the ballistic pattern is defined by the rapid and continuous sequence of the projectiles directed at the target. The projectiles do not generally follow each other on exactly the same path, and, as a consequence, a dispersed pattern is built up. The statistical characteristics of the resulting pattern generally involve three aspects. First, given target detection and assignment, there is the process involving certain random elements of bringing the gun to bear on target and keeping it on target during the engagement. From this process, the requisite gun orders are generated. Because the errors in tracking are both auto- and cross-correlated, so too are the gun orders generated. Superimposed on the tracking and gun-order generation process is the second aspect, viz., ballistic dispersion. This process also involves several random elements, but in a different manner from the first aspect. This random or ballistic dispersion varies from projectile to projectile, i.e., it is uncorrelated. Since the first aspect is superimposed on this aspect, the tracking and gun-order auto- and cross-correlations are induced on the sequentially-ordered projectiles as they are fired. The third aspect arises because many of the target engagement parameters--individual projectile hit probabilities, target vulnerability, auto- and cross-correlations, projectile times-of-flight, etc.--can and do change markedly during the engagement. These essentially Lexian effects must be accounted for since they can change at a rate equal to or greater than the gun cyclic rate of fire.
2. Prior Art
Terry and Hudock in U.S. Pat. No. 4,244,272, issued Jan. 13, 1981 have shown a mechanism to provide a predetermined and constant dispersion pattern of projectiles fired at a target by a fixed forward-firing Gatling-type gun by continually adjusting the alignment of the barrels of the rotating barrel cluster of the gun with respect to the mean boresight of the cluster as a function of the instantaneous slant range to the target and the average muzzle velocity of the projectiles.
Exemplary prior art is set out at length in U.S. Pat. No. 4,244,272, supra, and is hereby incorporated by reference. The prior art mechanisms apply only to multi-barrel guns. Further, except for U.S. Pat. No. 4,244,272, supra, no attempt has been made to develop an attendant logic for controlling these mechanisms, i.e., based on the engagement conditions to control the parameters of size, shape, density, and orientation of the ballistic pattern being progressively built up in the region of the target during the firing interval. These parameters, inter alia, collectively influence whether or not hits are obtained on the target and, more importantly, whether or not the target is damaged to some acceptable state.